27 Feb 2007

I spent the day at Earl’s Court, in London, visiting the Innovations for the Built Environment exhibition. It was surprisingly lively and none too big, which meant that you can get around it in two or three hours. It was nominally five separate exhibitions called 1) Ecobuild 2) Futurebuild 3) Regenex 4) Cityscape and 5) Building for Health, but in fact these were all just arranged as zones so that you can slip seamlessly between them. There was also a surprisingly comprehensive seminar programme with lots of well known industry names giving their time to talk about their work. Rather too many in fact because there were no less than nine free seminar theatres and four paid-for conference theatres, which meant that the casual visitor (i.e.me) was rather overwhelmed by the choice.

What was really noticeable was just how much the green agenda has taken over the mainstream construction industry. At an event like this four or five years ago, the world and their aunt would have been going on about modern-this and innovative-that, in the time honoured way. But now it seems it’s all carbon-carbon-carbon. The names and the businesses are still substantially the same, but there is now a mission to somehow save the planet, as well as being modern and innovative.

And perhaps not surprisingly, it has all become pretty competitive. The organisers had thoughtfully placed the stand belonging to the UK Timber Frame Association adjacent to the one run by the Modern Masonry Alliance. These two have been locking horns since….well, I am not sure since when, but it’s a decades old and rather tedious argument. But now they have a new variant to bash each other with. Which is the greener? Embodied energy v thermal mass. Biff, biff.

So I am walking around the exhibition thinking two contradictory thoughts at the same time. On the one hand: “My time has come, this is what I have been interested in for the past twenty five years and now everyone can see how important it all is.” And on the other? “The world has gone mad. This seems like some insane game about seeing who has got the greenest willy. This wasn’t what it was supposed to be about at all.”

At 3pm, I left, having had enough of all this green contradiction. I hit the Piccadilly Line with a copy of the Evening Standard. There was a two-page spread on the mayor’s latest plans for London. Now if anyone out there has Green Willy syndrome, it’s Ken Livingstone, the mayor. Today, he launched a call to reduce London’s carbon emissions by 60% by 2025, much sooner than the Kyoto agreement calls for. So far so good. But what measures is he actually suggesting? According to the article, which I have no way of verifying, Ken wants to tax aviation fuel to bring it in line with car fuel taxation: at the present time, aviation fuel is not taxed at all anywhere in the world, due to a 1947 United Nations convention. He’s far from the first person to call for this, but I am at a loss to know just how the Mayor of London could bring it about anymore than I could. It just not something that is in his remit. In fact, he knows damn well he can’t do it, so this amounts to a meaningless bit of green posturing on his part.

There are things that London’s mayor could arguably do though. If every light bulb in London was changed to a low energy one, it would save 575,000 tonnes of CO2 annually. Australia’s just done it: why not London? If all household appliances in London were 'A' rated ones, and standby buttons eliminated, it would save an additional 620,000 tonnes.

Large numbers for sure. But not when measured against the 44 million tonnes of CO2 London produces annually. And that’s not including aircraft movements into and out of the city, which are thought to account for an additional 23 million tonnes. These two measures combined would account for a saving of less than 3% when compared to the total output. Add in all the other measures he could conceivably introduce, like buses running on biodiesel, cavity wall insulation and cycling initiatives, and you still struggle to get much past a 7% or 8% saving on today’s figures. How do you square that with a projected saving of 60% within 18 years? Stick a few renewables on London’s roofs? You’re having a larf, Ken.

The things that would really drive down London’s carbon emissions (and the same goes for just about everywhere else in the Western world) are so painful that no one really dare face them. We are talking about stuff like the cessation of all economic growth, in fact a severe economic contraction, a “one child per family” policy, a ban on immigration, strict carbon rationing and something close to martial law in order to bring this all about. In order to have the carbon emissions of a third world city, London would have to become a third world city.

Does Ken Livingstone really want that? Does anybody? It’s all very well saying that unless we get our act together, we will shortly cook the planet to a crisp, but there remains this niggling little feeling inside me that we derive huge benefits from our carbon-rich lifestyle and that a future without burning carbon might just be worse than a future without ice caps.

That was my uneasy thought process as I caught the Cambridge Cruiser at 15.45 from King’s Cross. As it whizzed through Hertfordshire at 90mph, I reckoned that Ken Livingstone would have been pleased with me because I hadn’t taken the car down to London. In Green Willy world, I would have scored a point. I would shortly score another point as I disembarked at Cambridge and got on another train taking me one stop along the Ipswich branch line so that my trip home by car was only five miles, not fifteen. But taking the train instead of the car is another one of these marginal actions, like changing light bulbs. To really cut carbon emissions by a meaningful amount, I shouldn’t have gone to London at all. And I shouldn’t be sitting here at 21.30 with the computer on in a room bathed in light. We should simply not use electric lights or appliances of any description, except in emergencies. That is what a 60% carbon reduction would be like.

To be fair, it’s a dilemma we all seem to be caught up in. It’s easy for me to have a pop at Red Ken, but he’s only human and he is subject to the same stressors as everyone else. The construction industry is exactly the same, labouring under this illusion that there are two kinds of buildings, ordinary ones (bad ones) and sustainable ones (good ones), and that if they only build sustainable ones then everything in the garden will be rosy and our grandchildren will be dancing happily around on this lovely Blue Planet which we so thoughtfully bequeathed them. Whereas, what 60% carbon reductions actually translates at is…..STOP BUILDING NOW.

So am I getting terminally depressed by all this? Not quite, not yet, although I am feeling a little wobbly. There is of course the vague hope that the cavalry will come riding to the rescue and that we will come up with lots of carbon-free electricity in years to come and that we can forget about having to be careful with using the fossilised version. Or that some climate geeks will work out how to farm the atmosphere so that it starts working with us rather than against us. But this is all a bit too much like science fiction. There’s probably far more likelihood that we don’t manage to work out how to do anything clever like this, but will muddle on regardless.

In them meantime, I am beginning to feel like a British soldier in Iraq. I feel obliged to keep on fighting for greener, more elegant solutions in the built environment but at the same time a little voice inside me says I am wasting my time, that this is a battle we have already lost, and that we have to find another way out of this morass.

23 Feb 2007

Asbestos was widely used in the UK building industry through most of the last century. It was only during the 1980s that it started to become blacklisted and it was still being used, mixed with cement, through till 1999. It was used in all kinds of places: Artex was 2% asbestos until 1984, asbestos-cement roofing sheets, inside airing cupboards and around stoves and boilers, pipe lagging, ironing boards, night storage radiators, fire doors, artificial slates, wall boards. One of the most dangerous formats was a board made by Cape called Astbestolux, later replaced by an asbestos-free version called Supalux. There is a lot of asbestos about and if you get involved with demolition or renovation of an old building, you need to know how to handle the risk.

There are some fairly exacting requirements in place for commercial enterprises, including builders and demolition contractors. Every commercial building is now meant to have an Asbestos Register detailing if and where asbestos is located. But the situation with private householders is still largely unregulated, which means that if you have asbestos in your house you can more or less dispose of it as you wish. Except you can’t just take it to any old tip, but to one designated to take hazardous waste.

Whether this is a sensible idea is open to doubt. There is a big debate in asbestos circles about the exact nature of the risk involved. Everybody agrees that the really dangerous forms are brown and blue asbestos but white asbestos, which is the commonest one you are likely to come across, is less of a risk, especially when bound with cement. You have to breathe the dust to be at any danger at all, so an inert sheet of asbestos cement is not a significant risk, anymore than say an unopened packet of cigarettes.

There is a lot of confusion and fuzziness here. Caused in no little part by the activities of John Bridle and his Asbestos Watchdog business, which makes a living rubbishing mainstream asbestos claims. Bridle is of the opinion that there is an Asbestos Scare Industry out there which is all set rob us all blind by first finding asbestos where it isn’t and then charging us exorbitant amounts of money to remove it. Maybe Bridle is right, maybe he isn’t, but he has powerful friends in the media and gets a lot of exposure, mainly in the Sunday Telegraph.

The asbestos contractor I was speaking to wished, ruefully, that he made as much money as Bridle suggested he did. Just to stay in business as a licensed contractor, he has to pay £30,000 in insurance premiums every year for a business that turns over just under half a million. He said he thought it was quite possible that Bridle is right about white asbestos not being dangerous but he still had to remove it as if it was because he wouldn’t be allowed to practice otherwise. And there is also the distinct possibility that Bridle is wrong: lots of eminent scientists think white asbestos could well be harmful. If so, why take an unnecessary risk?

But the question which concerns me here is what exactly do you do when you are dismantling an old building and you want to know if any asbestos is present. I think it’s probably not a bad idea to have an asbestos survey at the outset. These cost anywhere between £100 and £500, depending on the size and complexity of the survey. The surveyor will most likely take a few samples which cost a further £10 or so each to analyse. My bill for vetting the 60s house we have just purchased was £111 inc VAT and including five samples. A good surveyor will then advise you of both the risks and the most appropriate way of handling them. As a commercial contractor, you are bound by law to dispose of asbestos in an appropriate manner but there is much less regulation placed on private householders. My local council, South Cambs, offers sealable sacks to householders to place their own asbestos remains in and there is one tip in the county you can take it all to, for which there is no additional charge. I guess they have to consider the alternative: fly tipping.

21 Feb 2007

I keep posting about Passive Houses and I must move on to something new. But before I get there, a query has come up that deserves a detailed response. What is the difference between a Passive House and a Passive Solar House? Are they the same thing? If not, how are they related? A bit of history is order here.

The Passive Solar HousePassive solar houses have been around a long time, arguably since we started putting windows in houses, whenever that was. It is a term used to describe a design principle that seeks to orientate a house so that the main living areas face the sun. The idea being that the sunshine heats the house, even on the most gloomy winter’s day, and that if the house contains enough heavy material, this free heat is stored overnight and slowly dissipates.

People got terribly excited about such concepts back in the 1970s and 80s. My very first building job, in 1980, involved doing a passive solar makeover of my house in Cambridge, carried out to the plans of Robert & Brenda Vale, who have since become the godparents of the UK’s green building movement. The house is still very much around (pictured here) and I revisited late last year: the current owner is aware of its history but is largely unimpressed by the thermal performance. “I don’t think my heating bills have been especially low, that’s for sure,” she told me, good-naturedly. She didn’t buy the house to save on heating costs: just as well.

Whereas it seems some climates, notably New Mexico and Arizona, seem to be ideally suited to passive solar designs, wet and cloudy Britain most definitely isn’t. That’s not to say that you can’t get any benefit from passive solar design, but it’s far more limited than its proponents make out. You have to build a high thermal mass house, which doesn’t suit everyone or every budget; you have to get the orientation right, which isn’t always possible; and you have to take extra measures to ensure you don’t suffer from summer overheating.

That’s not to say there isn’t still huge interest in passive solar as a design concept. Back in January, I was in the Building Centre Bookshop in London and there, on prominent display, was James Kachadorian’s The Passive Solar House. Kachadorian was custom homebuilder from Vermont who discovered passive solar design in the 1970s and built around 300 passive solar homes for his customers. He started designing in air ducts built into the floor, which he referred to as the Solar Slab and, despite lots of other people having very similar ideas at the time, he took out patents to try and protect his designs. When the patents ran out, he wrote the details up in this book, which he sees as a primer for passive solar designers.

However, his schemes started to unravel when there were outbreaks of mould inside his some of his air ducts and also when people started to realise that his houses certainly weren’t “homes without heating” which is how Kachadorian was (and continues) spinning it. “A beautiful, comfortable home that needs a backup furnace (boiler) or air conditioner only rarely” is how he puts it in the blurb of the book. But the text reveals a very different story: there is a still a significant heat load and a typical requirement is for a 12kW furnace, not small by current standards. Insulate the house better and you wouldn’t require nearly so much heat in the first place.

In fact, this is one of the problems with passive solar design. As you increase the amount of insulation in the fabric of the building, you decrease the heat load and you decrease the length of the heating season too. Instead of needing space heating on from say, September to April, a super-insulated house only requires it on from November to February. So your passive solar input just isn’t required so much and when you do need it, in the depths of winter, it’s delivering the least energy. The concept works best in the so-called shoulder seasons and, with a super-insulated house, you simply don’t need much extra heat at these times.

So the two principles, passive solar design and super insulation, are to some extent working against each other. In contrast to the Passive Solar Home, the German PassivHaus standard sits firmly in the super-insulation camp. Which begs another question. Why exactly did they call it PassivHaus?

PassivHausWhereas I think the original use of the term passive solar was to distinguish it from active solar, as used for specific applications like solar panels, the Germans seem to be using the term in a different sense which I can only liken to lying easy of the planet. Rather than actively consuming lots of the world’s resources, a PassivHaus will sit there in the background not doing any harm. Being passive, in fact.

Now a PassivHaus doesn’t need to be a passive solar house. It doesn’t need to be orientated towards the sun, nor does it requires tonnes and tonnes of thermal mass, though the great majority of German PassivHauses are masonry. These factors are taken into account on the modelling software used to determine the thermal performance of the design, and they will contribute to the overall performance, but they are not essential.

So in summary, passive solar house is a concept borne out of the first energy crisis in the 1970s and is all to do with using sunshine to heat the house. PassivHaus is a 90s concept, a rigorous performance standard emphasising the importance of super-insulation. As so often, Wikipedia is excellent on the differences in definition. Search on passive solar and passive house and you get two very different entries.

So what is a Passive House?

Passive HouseThe anglicised version of PassivHaus is not really defined at all. Hence the confusion. I have been using it interchangeably with PassivHaus, the German performance standard, but I guess there will be a lot of people around who are still far more familiar with the older concept of the Passive Solar House and will assume that this is what is being talked about. And I expect this confusion to persist for a while yet now that George Monbiot has latched onto the concept and seems to be writing about it frequently in his Guardian column. We can expect the phrase Passive House to get widespread media coverage in the months and years ahead.

But I wonder how many people will be aware of the nuances at work here. Or how many of them will just resort to the sloppy thinking which defines it as neither as a passive solar house nor a super-insulated house but simply as a House that doesn’t need a heating system. Which, as it turns out, is not the case for either meaning.

16 Feb 2007

There were a couple of moments when the PassivHaus study tour seemed to lose all contact with normality and enter into a surrealist daydream. Picture around 20 people, crammed into a cellar, with a few more hanging out in the passageway outside unable to get in for lack of space. We were listening, or trying to listen, to the architect, Carsten Grobe, who was explaining with the aid of a translator about the mechanical systems employed to heat the Passive House, which he had designed and built back in 1998 and in whose basement we were now standing.

One of our party asked what the carbon emissions were like for this house. Carsten gave a long and detailed explanation as to why the indoor air quality was very good and insisted that they had no problem at all with carbon emissions. It was an eloquent answer to a very different question.

You might think that this was just a translation problem and that he hadn’t understood the question. But similar misunderstandings happened throughout the tour. Whilst the Germans had no problem explaining how they have engineered these houses to reduce space-heating demand to an absolute minimum, they looked flummoxed when we started going on about carbon emissions or used the dreaded phrase “zero carbon.” I began to realise that these are concepts that the Germans actually felt uncomfortable about and it highlighted a surprising difference in emphasis between Germany’s PassivHaus builders and the UK’s “carbon busters.”

You see, it’s no accident that one of the key benchmarks for Passive Houses is a maximum allowance for space heating requirements for each house and it is expressed in kilowatt-hours per square metre per annum — 15 is the magic number they are looking for in this context. In contrast, the UK regs now work in terms of carbon dioxide emissions per square metre per annum. Whilst the two units are related, they are not the same, not by a long chalk.

The kilowatt-hour (kWh) has the benefit of being simple to understand. It’s the unit we buy our gas and electricity in, and the related kilowatt is the preferred unit of power for our boilers, fires and electrical equipment. Even light bulbs are routinely rated in watts. Most people are familiar and easy with the watt, the kilowatt and the kilowatt-hour.

Carbon dioxide emissions, in contrast, are much trickier. They vary a lot depending on the type of fuel being burned. A kWh of gas releases less than half the CO2 of a kWh of electricity. Every fuel has a conversion factor, related back to mains gas, and some fuels have several. So the fuel you choose to burn in your house has a critical effect on the CO2 emissions but no effect on the kWh you use. Consequently, Carsten Grobe saw no contradiction in using electricity exclusively to power his ventilation/warm air heating system and to heat his domestic hot water when the solar panels weren’t producing.

The three schemes we visited around Hanover were all different, designed to show the different aspects of PassivHaus living. Carsten Grobe’s selfbuild represented one strand, the upmarket detached family home: we also saw a block of flats in Hanover itself and a terraced house set out on the Expo site to the south of the city. The weather was wet — very wet in fact — but not particularly cold for February, around 7°C, and I was certainly a little surprised to find radiators on in both the detached house and the flat. In fact, I was surprised to even find radiators at all, though they were small and unobtrusive.

Most Passive Houses are built without radiators, except for towel radiators in bathrooms. They aim to maintain an even temperature throughout the structure and Carsten explained that the only reason they had a radiator in their house at all was for odd occasions when their elderly parents came to stay and they appreciated a bit of extra warmth.

But just because Passive Houses rarely use radiators, it doesn’t follow that Passive Houses are “Homes without Heating” as we sometimes think of them as being. The actual space heating arrangements vary from site to site but the overriding principle seems to be to a) having insulated the fabric down to a very low U value and having designed out all thermal bridgesb) you then fit energy-efficient triple-glazing into the openingsc) and then ensure that the resulting structure is virtually airtight.d) Now you build in a mechanical ventilation system to supply fresh aire) and you use a heat exchanger to take every available bit of heat from the extracted air and add it to the incoming air.f) You then pass this pre-heated air through something called a post heater (a term I had not come across before) which brings it up to a comfortable temperature.

How much work this post heater has to do depends on how warm you like your house. The one in the terraced Passive House was capable of delivering 1.5kW and could produce an air temperature of 50°C if required. I was frankly surprised at this: it seemed to me that this was essentially a warm air heating system.

The standard method of heating new homes in Germany is to use underfloor heating combined with a gas boiler. PassivHaus eschews this approach on the grounds that you don’t need a full heating system in a Passive House. But it seems to me to offer an alternative that is no cheaper to install and possibly burns more carbon because it relies on electricity to power the fans and the air heater. It would certainly be no cheaper to run because electricity is habitually three times the price of gas.

And yet Passive Houses sell themselves in part by saying that you can offset the extra costs of building to the higher standard by saving money on not having to install a full heating system. Hmm. I was beginning to have my doubts.

Carsten gave us another little trick used by PassivHaus designers. He said it was extremely difficult to get a really low theoretical heat demand from a detached two-storey structure as there is just too much external envelope in proportion to floor area. An easy way around this conundrum was to add a third storey, in his case a basement, and to include this in the heated envelope. The floor area goes up 50% whilst the space heating demand rises much less. As you are looking to meet a target expressed in kWh/m2/annum, the job of reaching PassivHaus standard becomes that much easier.

You could argue that this is daft and that the total energy load is actually increased in order to meet some notional standard. In fact, you’d be right but it’s a criticism that can be levied at most of the other energy rating schemes as well, certainly all the ones that work on a floor area basis.

Maybe, I am carping. I suppose I do carp rather a lot. But I know others were also uneasy. We had Julia Hailes, author of the Green Consumers Guide, with us in our party and she was flabbergasted to see that Carsten’s house was full of halogen and tungsten lights with not a CF bulb anywhere to be seen. There is in fact no particular requirement in the PassivHaus code to use energy efficient lighting or appliances: this seems bizarre. Julia also asked at one point just how you would incorporate a cat flap into a Passive House, a question that was met by complete bafflement from our hosts. Maybe the word cat flap was lost in translation, or maybe it was another case of different agendas.

The embodied energy question was raised several times by various delegates. Was the extra investment in, say, triple-glazing filled with krypton really worth it either financially or in terms of carbon emissions? Again, it seemed to be something that the Germans hadn’t addressed. They seemed to be solely interested in designing homes which required less than 15kWh/m2/annum for space heating: there didn’t seem to be any room for critical reflection about this.

The first day of the tour was spent in the hotel listening to various presentations. One of the most interesting presentations was delivered by John Willoughby, the energy consultant and sage, who gave a 20-minute slide show on the History of Low Energy Building in the UK. He ran through many projects starting with the Wallasey School (1961), the Wates House at CAT (1976 and still the best insulated building in Britain), various solar houses in the 1970s, the Pennyland and Linford projects in Milton Keynes in the 1980s, right through to Hockerton and Bedzed, both realised within the past few years. He also drew our attention to the increasing number of energy codes:• Code for Sustainable Homes• EST Good-Best-Advanced Standards• Eco Homes• Bill Dunster’s Zed Standard• PassivHaus• AECB Gold and Silver Standard

He suggested we were becoming good at standards but not very good at implementing them. He also referred to another energy sage, David Pickles, who I remember seeing give a talk once where he said that low energy living is 10% technology and 90% lifestyle. This little aphorism kept plopping into my head as we made our way around the three Passive House sites the following day. The German PassivHaus builders really didn’t seem to care about this aspect of energy efficiency at all: they just wanted to get their buildings up to PassivHaus standard and move onto the next one. PassivHaus seems to be very much an engineering concept, designed to provide comfortable space heating with the minimum energy possible. But that, unfortunately, is it.

So I came away feeling PassivHaus is a flawed standard. It’s very good on space heating demand (in advance of anything we have built in the UK, except for a tiny number of exemplar projects like Bedzed), but questionable on heat delivery systems, so-so on hot water heating and almost non-existent on lighting and electrical goods used within the home. What is more, there don’t appear to be any plans to update or improve the PassivHaus standard to take into account the rising concerns about carbon emissions. As such, I really don’t see PassivHaus translating wholesale across to the UK, but we can certainly learn a lot from what they have achieved to date.

The principle lesson perhaps being that, whilst it is all too easy for me to carp on about what is wrong with the PassivHaus standard, or why it is not quite the dog’s bollocks (try translating that!), they have built loads of them. And the more they build, the less theoretical it becomes and the more practical it appears. Whereas we may be full of good intentions, the Germans (and the Austrians, who seem to be even more enamoured of PassivHaus than the Germans) have now built around 6,000.

They are also very keen to promote the PassivHaus concept to the non-German speaking world. To this end, the next PassivHaus annual conference will for the first time be bi-lingual in German and English. So if you want to go and learn more about it, you need to head for Bregenz in Austria on April 13/14.

15 Feb 2007

First stop on our tour was this owner-architect built passive house in Ottbergen. The house was built in 1998 and is on three floors, each just over 100m2.

Carsten Grobe, the owner-architect, gave us a guided tour and spoke at length about construction and the mechanicals which are used to provide heating.

John Letton, MD of Formworks UK, pictured here in the living room of the Ottbergen house. Behind him are the triple-glazed window units complete with integrated blinds.

Our second stop was this block of Passiv Flats in Hanover, designed by architect Christian Grubert who was on hand to show us around.

The flat we looked at had a surprisingly large radiator in the living room which was definetly hot. In fact this flat has radiators in all the rooms.

Our group seemed to spend an inordinate amount of time in basements and cellars, looking at various bits of plant. Here under the Hohe Strasse flats, the architect explains how the building is heated and ventilated. The main point of interest here was a pellet boiler.

Our last port of call was a series of terrace houses at Kronsberg, a new development to the south of Hanover on the EXPO site. These 32 terraced houses are all built to the PassivHaus standard and have been extensively monitored. Note that each flat has a turf roof. The two projecting poles through the roof are the inlet and outlet for the ventilation system.

These particular houses are hybrid timber frame and masonry. The gable walls and party walls are precast concrete: the walls between are timber frame. Here is a cut away of the timber frame walls exhibiting 300mm of insulation.

These terraces have no basement, unusual for new housing in Germany. The plant room is consequently in the loft, pictured here. Here John Willoughby and Gavin Hodgson (BRE) inspect the loft with our guide. The whole site is fed by a CHP plant which supplies pumped hot water into all homes. This is one of the pipes in the LH wall. To the right of the hot water tank is a post heater, wrapped up in silver foil.

10 Feb 2007

Tomorrow I am off on a Passive House (PassivHaus) study tour. I take an evening flight to Hanover and join seventy others at the Loccumer Hof Hotel for a day of lectures on Monday followed by a full day’s itinerary visiting three PassivHaus sites. Sandwiched between this is a gala evening meal at Hanover City Hall for which they have thoughtfully emailed us the menu. It looks to consist of about half the annual produce of Lower Saxony and I don’t anticipate many of the guests will be clubbing into the small hours after that lot.

For those of you who know little or nothing about Passive Houses or, more specifically, the PassivHaus standard, I can’t do better than to suggest you mug up at the relevant Wikipedia page.

The Passive House concept is beginning to get wide coverage in the UK media. It’s seen as the most advanced example of low energy housing anywhere on the planet and over 6,000 have been completed to date, mostly in Germany and Austria. In the UK, the BRE have taken it under their wing and it is they who are organising this study tour. The question we will no doubt all be asking is: “Is this the future of low carbon housebuilding?”

Whilst there are lots of plus points, there are also serious doubts in my mind about whether the PassivHaus standard is the perfect solution. In particular, what irks me most is that it sells itself as a performance standard – it is quite specific about just how much energy can be consumed per square metre of floor area — but it also adds several other stipulations about what you can and can’t include in a passive house. For instance, you must have mechanical ventilation with heat recovery, whether you want it or not, and you must have windows with ultra-low U values. Why is it so prescriptive about these items? Are they saying you can’t meet the performance standard without these features? Or is there some other reason for including them?

They say that passive houses can be either masonry or timber frame? But German timber frame is very different to British timber frame: is our local version of timber frame suitable or does it need more thermal mass? What about using other build systems like SIPS or ICFs?

There are also lots of issues to discuss like costs and transferability to other nations? As discussed on the blog recently, the UK has the smallest homes in Europe. It’s harder to lose 300mm of wall insulation in a rabbit hutch. Does it make sense to do so? And does the standard restrict house design to the rectangular box? Or can it be adapted to the more varied UK styles?

Another issue is the requirement for triple glazing: is the extra expense, not to mention the embodied energy used in manufacture, ever justifiable in the British climate? In fact, I hope the whole house embodied energy argument gets aired. It’s hardly worth reducing the annual carbon emissions from 5 tonnes to 2 tonnes if it’s going to take an extra 60 tonnes of carbon to manufacture and build. Whether it does or doesn’t, I have no idea. But it’s the time and the place to speculate about these issues and I’ll be posting my answers when I get back mid week.

7 Feb 2007

The Mac is cool in a way it’s never been before. Whereas ten years ago, people were forecasting the demise of the platform and citing it, along with the Betamax video recorder, as an example of a better technology that simply got swept away by overwhelming market forces, today the Mac is doing surprisingly well in terms of market share and in winning new admirers across from Windows.

I have been using Macs since I started desktop publishing. In fact I switched straight from the venerable Amstrad PCW (1987-1993) to the Mac without ever owning a PC. Our household currently has four of the beasts and we’ve probably migrated through another four or five since getting my first one 15 years ago. Add in numerous screens, laser printers and other accessories, not to mention at least seven iPods at the last count, and you can see that Apple has done pretty well out of our household.

But that’s an awful lot of hardware and an awful lot of it is now defunct or nearing the end of its useful life. And recently, the spotlight has started to be shone directly at Apple to see how it stacks up environmentally. MacUser (19 Jan 2007) has an article entitled “How Green is Your Apple?” which takes a look at some of these issues.

The very basic question you might want to know the answer to is how much power does the computer consume? You’d think that somewhere in the control panels or system preferences it might tell you. But, if it does, I have never been able to find out where. There is a panel called About This Mac which has a page on System Power Settings. It has nothing about power usage. There is a System Preference window entitledEnergy Saver: it tells you how to put the computer and the display into Sleep Mode and lets you adjust how quickly you can do this, but there is no information about how much power you will save by doing this. To get this information, you have to trawl around the web and check out independent sources. The very fact that you have to do this shows how reluctant the manufacturers are to divulge this information. Can you imagine buying a light bulb and having to check on the web to find out what the wattage is?

In fact, one site run by Michael Bluejay, has the basic information I was looking for for the Mac I currently use, the iMac G5 with in-built 20” LCD screen (very nice it is too). It seems to vary from about 120 watts, doing stuff like watching a DVD or opening pictures, through 97 watts when very little is happening. The monitor consumes about 30 watts — LCD monitors use about half the power of the old CRT ones — and the computer itself about 60 or 70 watts. Putting everything into sleep mode cuts consumption right down to 3.5 watts. Interestingly, turning it off doesn’t completely cut out power usage: it still uses 1.5 watts. Only by unplugging it altogether does it stop using any power at all.

But another question arises. What is the embodied energy of my Mac? How much energy was consumed in building it? An academic at Arizona State University, Eric Williams, has attempted to work this out and has come to the conclusion that a desktop computer with a 17” monitor will consume 6400 megajoules in production. Put into a power unit more readily comprehensible (by me at least,) one megajoule is equivalent to 0.2778kilowatt hours, so 6400 megajoules = 1778kWh. That’s equivalent to around 20,000 hours computing time at 90watts an hour, which is probably two or three times longer than the typical desktop computer gets used for in its lifetime. Wow. That’s a lot. If you include this embodied energy into your calculations it means that every hour you run your computer it uses not around 90watts but 300 – 500 watts.

Why does it take so much power to produce a computer? Williams estimates that chip production is very energy intensive. A 32MB DRAM chip may only weigh 2 grams but it requires “1.6kg of fossil fuel, 72g of associate chemicals and a whopping 32kg of water to create.”

In addition, the manufacture of computers involves using lots of obscure and possibly dubious chemicals such as germanium, tantalum, mercury and even arsenic. It’s all resulted in Greenpeace running a campaign called Green My Apple. I’ll be honest: a lot of Greenpeace campaigns leave me cold, but this one is done with wit and style and it’s hard not to be won over by it. It’s good to shine the spotlight at what goes on in the dark underbelly of this industry.

But the real problem with computers in particular is that they are disposable. Computer companies depend on dreaming up new products all the time. The hardware companies do it. The software companies do it. The new software demands new hardware and the new hardware makes new software innovations possible. It’s been a very good development model for the past 25 years but maybe we have to start looking at a future where computers are built to last 20 years, not four. It’s been an industry subsumed by innovation and growth: maybe its time is up.

5 Feb 2007

At the end of last week, we completed the purchase of a house that we plan to demolish and replace. It’s just six miles away in the village of Linton and it’s going to be quite an upheaval after 15 settled years in our current house, which we built back in 1992. Our three boys were three, 18 months and six months old when we moved in here: it was little better than a building site. But looking back, they were good times. Somehow the boys have survived the intervening years and the eldest — the renowned shower fiend — is about to celebrate his coming of age.

So why move now? The house we have is lovely, the surroundings are great and the neighbours are on the whole pretty friendly. There are gripes: mostly at the moment to do with the continual ferrying of our teenagers around at all hours of the day and night. Weston Colville isn’t exactly blessed with much in the way of public transport whereas Linton at least has a half hourly bus service into Cambridge. But as friends have pointed out, the teenage ferrying years don’t go on forever and we are probably almost half way through them, so this in itself is not a good reason to move.

No, the real reason we are moving is that I relish the challenge of creating a new house and nobody has screamed loudly enough to stop me. I have been looking at sites for ages and have once or twice bid on plots and barns, only to be outbid by people more bullish than me. But in October we came across a site that we really liked in a road where we had looked at another house five years previously and, after much soul-searching, we decided to put in a good bid, close to the asking price.

This knocked out all the professional developers who would normally be scanning for sites like this, a tired 60s house on a large plot. The only way a developer could possibly hope to make a turn on this site would be by building two houses on it, which would be technically possible as the garden could be easily subdivided. But the large garden is precisely what attracted us to the site in the first place and we are rich and lazy enough not to worry about having to maximise every ounce of value from a site. And also not to have to move into a rented house or a caravan. No, this project is going to be done at the comfortable, bridging-loan end of the selfbuild spectrum.

The house we hope to build will be about the same size as the one we already live in, that is about 200m2. In fact, it’s not even that much bigger than the 60s house that is already there. But our hope is that it will be a whole lot lovelier. Exactly what we are going to put there remains to be seen, but the blog will be covering the story as it unfolds.